Power Transmission Path Research Articles

Locomotive dynamic performance under traction/braking conditions considering effect of gear transmissions

ABSTRACTTraction or braking operations are usually applied to trains or locomotives for acceleration, speed adjustment, and stopping. During these operations, gear transmission equipment plays a very significant role in the delivery of traction or electrical braking power. Failures of the gear transmissions are likely to cause power loses and even threaten the operation safety of the train. Its dynamic performance is closely related to the normal operation and service safety of the entire train, especially under some emergency braking conditions. In this paper, a locomotive–track coupled vertical–longitudinal dynamics model is employed with considering the dynamic action from the gear transmissions. This dynamics model enables the detailed analysis and more practical simulation on the characteristics of power transmission path, namely motor–gear transmission–wheelset–longitudinal motion of locomotive, especially for traction or braking conditions. Multi-excitation sources, such as time-varying mesh stiffness and nonlinear wheel–rail contact excitations, are considered in this study. This dynamics model is then validated by comparing the simulated results with the experimental test results under braking conditions. The calculated results indicate that involvement of gear transmission could reveal the load reduction of the wheelset due to transmitted forces. Vibrations of the wheelset and the motor are dominated by variation of the gear dynamic mesh forces in the low speed range and by rail geometric irregularity in the higher speed range. Rail vertical geometric irregularity could also cause wheelset longitudinal vibrations, and do modulations to the gear dynamic mesh forces. Besides, the hauling weight has little effect on the locomotive vibrations and the dynamic mesh forces of the gear transmissions for both traction and braking conditions under the same running speed.

원거리 전기 자동차의 다중 충전을 위한 레이저 파워 빔 기반의 무선 전력 전송 시스템

This paper presents the design and simulation of a laser power beaming (LPB) system for an electric vehicle that establishes an optimal power transmission path based on the received signal strength. The LPB system is possible to transfer power from multiple transmitters to a single receiver according to the characteristics of the laser and the solar panel. When the laser beams of multiple transmitters aim at a solar panel at the same time, the received power is the sum of all energy at a solar panel. Our proposed LPB system consists of multiple transmitters and multiple receivers. The transmitter sends its power characteristics as optically coded pulses with a class 1 laser beam and powers as a high-intensity laser beam. By using the attenuated power level, the receiver can estimate the maximum receivable powers from the transmitters and select optimal transmitters. Throughout the simulation, we verified the possibility that different LPB receivers were achieved their required power by the optimal allocation of the transmitter among the various transmitters.

Design of 3-Speed Bicycle Transmission Hubs

This paper presents the embodiment designs of 3-speed transmission hubs which consist of basic planetary gear mechanisms and gear-shifting control mechanisms. Two feasible clutching sequence tables are synthesized by analyzing the kinematic structure of the gear mechanism. A mechanical control mechanism is used to control the engagement or disengagement of each clutch to guide the power flow from the rear sprocket via the gear mechanism to the hub shell. The power transmission path at each gear stage is further checked to verify the validity of the transmission hub. The embodiment designs of two 3-speed transmission hubs are presented.

The Effect of High Power at Microwave Frequencies on the Linearity of Non-Polar Dielectrics in Space RF component

In satellite communication systems, there are high power multichannel transmitters and wideband receivers that have shared RF antenna transmission lines because of: 1) large power level difference between the transmitted and received signal; 2) limited frequency channels. The harmonics and Passive Intermodulation (PIM) Interference will be generated due to passive non-linearities in the high power transmission path. This can be a serious problem. This paper describes how to determine the signal levels and dominant mechanisms that are associated with non-linear dielectric behavior in this context. A novel measurement system for testing dielectric samples is described and measurement results are provided for commonly used microwave dielectrics.

Effect of induction heating on fatigue life of drive plate for dual mass flywheel

A dual mass flywheel has positive effects on noise and vibration problems, but there are still difficulties securing sufficient component durability during the development process to increase the output. In this study, the fatigue life of a drive plate, a component in the power transmission path that is often fractured by cyclic loading, is evaluated in relation to heat treatment, and the effect of heat treatment on the fatigue life is studied. For this purpose, a fatigue test and rig test are conducted on both the raw material and heat-treated material of the drive plate. Based on the fatigue material properties obtained from the fatigue tests and the boundary conditions of the rig test, a fatigue analysis is conducted to predict the fatigue life. The heat-treated material has a fatigue life five times longer than the raw material in both the rig test and fatigue analysis. The fatigue life evaluation method is validated through a comparison of the life predicted by the fatigue analysis and the test results of the rig test.

Design and Analysis of a Novel Speed-Changing Wheel Hub with an Integrated Electric Motor for Electric Bicycles

The aim of this paper is to present an innovative electromechanical device which integrates a brushless DC (BLDC) hub motor with a speed-changing wheel hub stored on the rear wheel of an electric bicycle. It combines a power source and a speed-changing mechanism to simultaneously provide functions of power generation and transmission for electric bicycles. As part of the proposed integrated device, the wheel hub consists of a basic planetary gear train providing three forward speeds including a low-speed gear, a direct drive, and a high-speed gear. Each gear is manually controlled by the shift control sleeve to selectively engage or disengage four pawl-and-ratchet clutches based on its clutching sequence table. The number of gear teeth of each gear element of the wheel hub is synthesized. The BLDC hub motor is an exterior-rotor-type permanent-magnet synchronous motor. Two-dimensional finite-element analysis (FEA) software is employed to facilitate the motor design and performance analysis. An analysis of the power transmission path at each gear is provided to verify the validity of the proposed design. The results of this work are beneficial to the embodiment, design, and development of novel electromechanical devices for the power and transmission systems of electric bicycles.

Novel Ultra-Wideband Bandpass Filter Using Shorted Coupled Lines and Transversal Transmission Line

A novel ultra-wideband (UWB) bandpass filter using two shorted coupled lines and a 270° transversal transmission line is proposed. The two shorted coupled lines are utilized to realize 180° phase inversion, while a folded transversal transmission line of 270° is introduced to perform as another power transmission path. Good impedance matching, UWB passband and wider upper stopband can be achieved. One prototype is fabricated for demonstration, good agreement is observed between simulated and measured performances of the UWB filter, indicating a fractional bandwidth of 124.6% (3-11.6 GHz).

Power flow model of flexural waves in finite orthotropic plates

In this paper, an approximate power flow model is developed for the analysis of the flexural waves in finite orthotropic plate transversely vibrating in the medium-to-high frequency ranges. The derived energy equation for the model is expressed with time- and locally space-averaged farfield wave energy density. It could be the more general form than that of the conventional power flow analysis model seen in the isotropic plate. With the derived model, dynamic characteristics varying with the direction can be expressed. To verify the validity and accuracy of the model, numerical analyses are performed for the case where a finite rectangular plate is excited by a harmonic point force, and the calculated results expressed with the energy levels are compared with classical modal solutions by changing the frequency and the damping loss factor of the plate. The dominant power transmission paths in the plate are also predicted from the distribution of the approximate intensity fields.

Underground 161 kV transmission project in Des Moines, Iowa

The design of a 161 kV XLPE-insulated underground cable installed in Iowa Power and Light Company's transmission line system and its accessories is described. The cables, cable terminators, and cable splices were designed specifically to provide an underground electric power transmission path through downtown Des Moines, Iowa. Electrical characteristics, thermomechanical design, and installation are covered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>